JPH03186421A - Suspension control device - Google Patents

Abstract

PURPOSE:To make it possible to set control modes clearly different from each other by changing, through a mode selecting means, responsiveness from generation of vibration in a car body in the vicinity of a suspended resonance frequency to forced setting of damping force of a shock absorber or responsiveness of releasing forced setting. CONSTITUTION:A change of vibration of a car body is detected by a means M2 while abstracting vibration in the vicinity of a suspended resonance frequency of the car body by a means M3 being based on a detecting result of the means M2. When amplitude of the abstracted vibration exceeds a threshold value, the damping force characteristic of a shock absorber M1 is forcedly set to a high side by a means M4. Further forced setting of damping force is released by a means M5 being based on the above mentioned abstracted amplitude. On the other hand, a control mode of damping force of the shock absorber M1 is selected by a means M6. Responsiveness from generation of vibration in the car body in the vicinity of the suspended resonance frequency to forced setting of the damping force or responsiveness of releasing the forced setting is respectively changed by a means M7 in accordance with switching of a mode.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a suspension control device. Regarding a control device.

[Prior Art] As this type of suspension control device, there is one that detects changes in vehicle vibration based on changes in road surface conditions and changes the damping force characteristics of a shock absorber to a higher or lower side. For example, when the rate of change in the damping force of the shock absorber is detected E2, and this rate of change exceeds a predetermined threshold value, that is, when the damping force suddenly changes due to unevenness of the road surface, brake operation, etc. A device is known that quickly switches the generation pattern of damping force against movement from a high side to a low side (Japanese Patent Laid-Open No. 64-67407).
Publications, etc.). Since the rate of change in damping force is a signal with extremely high responsiveness, such a suspension control device can quickly follow changes in the damping force pattern to changes in road surface conditions and maintain good ride comfort.

[Problems to be Solved by the Invention] However, such suspension control devices only switch the setting of the damping force of the shock absorber from a high side to a low side or vice versa when a predetermined condition is met, so it is difficult for the driver to It is not easy to change the control of the damping force characteristics of the shock absorber so that it places more emphasis on ride comfort as a whole, or more on steering stability, depending on the driver's intention.

That is, it is difficult to set the control mode for the damping force of the shock absorber (for example, to set a normal mode that prioritizes riding comfort or a sports mode that prioritizes handling stability).

In addition, the applicant of the present application (in Japanese Patent Application No. 1-235232) proposed an invention for improving the above-mentioned conventional suspension device in terms of ride comfort and steering stability when the road is flat or rough. However, with this invention, if the hard or soft conditions become unbalanced due to continued use of either a flat road or a rough road, this can be corrected and the balance between steering stability and ride comfort can be maintained.As a result, It becomes even more difficult to set multiple control modes for the shock absorber.

SUMMARY OF THE INVENTION An object of the present invention is to provide a suspension device that can easily switch the control mode of a shock absorber and set the control mode based on the driver's intention.

The configuration of the present invention that achieves the above object will be described below.

[Means for Solving the Problems] The suspension control device of the present invention (as illustrated in FIG. Alternatively, in a suspension control device that suppresses vehicle body vibration by changing to a lower side, a vehicle body vibration detecting means M2 detecting a change in vibration of the vehicle body, and a sprung resonance frequency of the vehicle body is determined based on a detection signal from the vehicle body vibration detecting means M2. vibration extracting means M3 for extracting vehicle body vibration with a frequency near , and a damping force characteristic of the shock absorber whose damping force is to be changed when the amplitude of the extracted vehicle body vibration exceeds at least a threshold value. A damping force setting means M4 that forcibly sets the damping force to a higher side, a forced setting canceling means M5 that cancels the forced setting based on the extracted vehicle body amplitude, and a control mode of the damping force of the shock absorber M1 are switched. Depending on the selection of the mode switching means M6 and the mode switching means M5, the response from the occurrence of vibration at a frequency close to the sprung mass resonance frequency in the vehicle body to the forced setting, or the responsiveness to the cancellation of the forced setting is controlled. Responsiveness changing means M7 to change
It is characterized by comprising:

In addition, as a mode of the responsiveness changing means M7 (for example, 1) a mode of switching the above-mentioned threshold according to the selection of the mode switching means M6 (when the threshold is increased, the responsiveness of the above-mentioned forced setting is (b) Shock absorber M as a detected object used to detect vehicle body vibration by vehicle body vibration detection means M2
1 from the front wheel side to the rear wheel side or vice versa (if detected on the rear wheel, the responsiveness of the above forced setting will decrease), and (c) the period from when the above threshold is exceeded until the forced setting There are two ways to change the time (longer this time (1) the responsiveness of the above forced setting will decrease) and (2) longer time until the forced setting is canceled (1) longer time until the forced setting is canceled. (responsiveness decreases).

[Function] The suspension control device of the present invention having the above configuration has the following features:
While the vehicle is running, changes in vibration of the vehicle body are detected by vehicle body vibration detection means M2. Among the detection signals by the vehicle body vibration detecting means M2, vehicle body vibrations having frequencies near the sprung mass resonance frequency are extracted by the vibration extracting means M3. The extracted signal (
It captures the damping force that occurs when the vehicle height changes near the sprung mass resonance frequency, which is a large vehicle height change (t, so-called vehicle body tilt) near the sprung mass resonance frequency. This is a signal that can be used to determine the occurrence of vibrations, which are the main cause of motion sickness.

When the damping force setting means M4 satisfies at least the condition that the amplitude of the damping force detection signal extracted by the vibration extraction means M3 exceeds the threshold value (other conditions such as continuing to exceed the threshold value for a predetermined time) (may be necessary), shock absorber M
The suspension is set to be hard in order to prevent the vehicle from rolling by forcibly switching the damping force from the low side to the high side. Then, this strong hardware setting can be canceled by forced setting canceling means M5 based on the extracted damping force detection signal.

When implementing such control, depending on the mode selected by the mode switching means M6, the responsiveness from the occurrence of vibration (tilt) at a frequency near the sprung mass resonance frequency in the vehicle body to the forced setting or the forced setting is determined. Responsiveness of setting cancellation,
This is changed by the responsiveness changing means M7.

By changing the response to tilting in this way, in a certain mode selected by the mode switching means M6, the damping force characteristic of the shock absorber M1 is smoothly switched to the high side, and in the -labor mode, the damping force characteristic is The switch to the higher side becomes relatively gradual. As a result, a plurality of control modes for the damping force characteristics of the shock absorber are clearly set.

[Embodiment 1] In order to further clarify the structure and operation of the present invention, a preferred embodiment of the suspension control device of the present invention will be described below. FIG. 2 is a schematic configuration diagram showing the configuration of this suspension control device. Figure 3 (A
) is a partially cutaway overall configuration diagram of the shock absorber, and FIG. 3(B) is an enlarged sectional view of the main part of the shock absorber.

As shown in FIG. 2, a suspension control device 1 (variable damping force type shock absorber (hereinafter simply referred to as shock absorber) 2FL) of the present embodiment.

2FR, 2RL, 2RR5 and an electronic control device 4 that is connected to each of these shock absorbers and controls their damping force.

Shock absorber 2FL, 2FR, 2RL,
As will be described later by 2RRi, the shock absorber 2FL
, 2FR.

A piezo load sensor that detects the force acting on 2RL and 2RR, and shock absorbers 2FL, 2FR, and 2
R.L.

Each set includes a Viezo actuator that switches the generation pattern of the 2RR damping force.

Also, each shock absorber 2FL, 2FR, 2RL
.

2RR has left and right rear wheels 5 Fi, 5 FR, respectively.
5R1-, 5RR suspension lower arm 6FL
, between 6FR, 6RL, 6RR and the vehicle body 7,
Coil spring 8FL, 8FR, 8RL, 8
It is attached to RR.

Next, each of the above shock absorbers 2FL and 2FR.

The structure of 2RL and 2RR will be explained. In addition, each of the above shock absorbers 2FL, 2FR, 2RL, 2R
Since the structure of R is all the same, here we will use the left front wheel SFL.
This will be explained by taking the side shock absorber 2FL as an example. In addition, in the following explanation (the suffix (FL) of the code attached to the upper hook member)
.

FR, RL, RR) may be omitted as necessary.

The shock absorber 2, as shown in FIG. 3(A),
The lower end of the cylinder 11 side is fixed to the suspension lower arm 6 via the axle side member 11au.On the other hand, the bearing 7 is fixed to the upper end of the rod 13 inserted through the cylinder.
It is fixed together with a coil spring 8 to the vehicle body 7 via a vibration-proof rubber 7b.

Inside the cylinder 11 (inner cylinder 15 connected to the lower end of the rod 13, connecting member 16 and cylindrical member 17)
and a main piston 18 that is slidable along the inner circumferential surface of the cylinder 11. Shock absorber 2
A piezo load sensor 25 and a piezo actuator 27 are housed in the internal cylinder 15 connected to the rod 13 (upper).

The main piston 18 is fitted onto the outside of the cylindrical member 17, and a sealing material 19 is interposed on the outer periphery of the main piston 18, which fits into the cylinder 11. Therefore, the inside of the cylinder 11 (above) is divided into a first liquid chamber 21 and a second liquid chamber 23 by the main piston 18. A backup member 28 is screwed to the tip of the cylindrical member 17. Between the cylindrical member 17,
Together with the main piston 18, a spacer 29 and a leaf valve 30 are pressed and fixed to the cylindrical member 17 side, and a leaf valve 31 and a collar 32 are pressed and fixed to the backup member 28 side. In addition, a main valve 34 and a spring 35 are interposed between the leaf valve 31 and the backup member 28, and the leaf valve 31 is connected to the main piston 18.
It is biased in the direction.

These leaf valves 30, 311i are in a state where the main piston 18 is stopped (the upper extension side and the contraction narrow passage 18a provided in the main piston 18).

18b are each closed on one side, and the main piston 1
8 opens to one side as it moves in the direction of arrow A or B. Therefore, the hydraulic oil (
As the main piston 8 moves, both passages 18a
, 18b to move between the two liquid chambers 21, 23. In this way, both liquid chambers 21. ．． 23 in a state where the movement of hydraulic oil is limited to both passages 18a and 18b
The damping force generated against the movement of the rod 13 is large, and the suspension characteristics become hard.

A piezo load sensor 2 is housed inside the internal cylinder 15.
5 and the piezo actuator 27 are shown in FIG. 3(A),
As shown in (B), this is an electrostrictive element laminate in which thin plates of piezoelectric ceramics are stacked with electrodes in between. Each electrostrictive element of the piezo load sensor 25 (is polarized by the force acting on the upper shock absorber 2, that is, the damping force. Therefore, the output of the piezo load sensor 25 can be taken out as a voltage signal by a circuit with a predetermined impedance. rate can be detected.

The piezo actuator 271 is made by stacking electrostrictive elements that expand and contract with good response when a high voltage is applied to increase the amount of expansion and contraction, and directly drives the piston 31.

When the piston 31 is moved in the direction of arrow B in FIG. 3(B), the plunger 37 and the spool 41 having a mouth-shaped cross section are also moved in the same direction via the hydraulic oil in the oil-tight chamber 33. When the spool 41 in the position shown in FIG. 3(B) (origin position) moves in the direction B in the figure, the first liquid chamber 2
The sub-flow path 16c connected to the liquid chamber 1 and the sub-flow path 39b of the bushing 39 connected to the second liquid chamber 23 are communicated with each other. The flow path 17 in this sub flow path 39b [i and the cylindrical member via the oil filler 45a provided in the plate valve 45] 7
Since the spool 41 is moved in the direction of the arrow B, the flow rate of the hydraulic oil flowing between the first liquid chamber 21 and the second liquid chamber 23 increases as a result. In other words,
Shock absorber 2 (Yo Piezo actuator 27
When it expands due to the application of high voltage, its damping force characteristics switch from the state of high damping force (hard) to the state of low damping force (soft), and when the charge is discharged and contracts, the damping force characteristic changes to the state of high damping force (hard). restore the condition.

The leaf valve 31 provided on the lower surface of the main piston 18 is moved by a spring 35.
It is regulated compared to 0. In addition, an oil filler 45b having a larger diameter than the oil filler 45a is provided outside the oil filler 45a in a plate valve 45 slidably provided in an end space 39c following the sub flow path 39b. valve 45
When the bushing moves in three directions against the biasing force of the spring 46, it becomes movable through the upper oil hole 45b of the hydraulic oil 1.

Therefore, regardless of the position of the spool 41, the hydraulic oil flow rate 1 when the main piston 18 moves in the direction of arrow B.
It becomes larger than when the main piston 18 moves in the direction of the arrow claw. That is, the damping force is changed depending on the moving direction of the main piston 18, thereby improving the characteristics as a shock absorber. Also, oil tight room 3
A hydraulic oil replenishment path 38 is provided between the oil-tight chamber 33 and the first liquid chamber 21 together with a check valve 38a to maintain the hydraulic oil flow rate in the oil-tight chamber 33 at a constant level. The partition wall 41a of the spool 41 has an oil passage 41d, the annular groove 40 of the spool 41 has an oil passage A, and a lower communication hole 41 with a diameter larger than the diameter of 1d.
e is opened.

Next, the electronic control device 4 that switches and controls the damping force of the shock absorber 2 described above will be explained using FIG. 4.

This electronic control device 4 includes a piezo load sensor 25 for each shock absorber 2, a steering sensor 50 (not shown) which is a sensor for detecting the running state of the vehicle and detects the steering angle of a steering wheel, and a steering sensor 50 for detecting the running speed of the vehicle. A shift position sensor 52 that detects the shift position of the transmission (not shown) that changes the speed of the engine and outputs it, and a stop lamp that issues a signal when the brake pedal (not shown) is stepped on. switch 53;
A mode changeover switch MS is connected to which the control mode of the damping force characteristics of the shock absorber 2 can be selected.

The electronic control device 4 outputs control signals to the piezo actuator 27 described above based on the detection signals of the piezo load sensor 25 of each shock absorber 2 and the detection signals of various sensors that detect the running state, etc. The electronic control device 4 includes a CPU 4a, a ROM 4b,
The input section 4e is configured as a logic operation circuit centered around the AM4e and is connected to these via a common bus 4d.
And input/output with the outside is performed by the output section 4f.

The electronic control device 4 includes a damping force detection circuit 54 to which a piezo load sensor 25 such as CPtJ4a is connected, a low-pass filter 55 to which the damping force detection circuit 54 is connected, and a bypass filter to which the output of the low-pass filter 55 is input. 56, steering sensor 50 and vehicle speed sensor 51
A waveform shaping circuit 57 connected to the piezo actuator 27 (a high voltage application circuit 58 connected to the piezo actuator 27, a battery 61
a so-called switching regulator type high voltage power supply circuit 62 that boosts the voltage of the battery 61 and outputs a drive voltage for driving the piezo actuator; 64
etc. are provided.

The above damping force detection circuit 54. Bypass filter 56, waveform shaping circuit 57. The shift position sensor 52.degree. stop lamp switch 53 is connected to the input section 4e, and the high voltage application circuit 58.
Output circuit 60. The high voltage power supply circuits 62 are each connected to the output section 4f.

Note that an ignition switch 63 is interposed between the battery 61 and the power source 64.

The damping force detection circuit 54 includes each piezo load sensor +J-25FL.
, 25FR, 25RL, and 25RR, each detection circuit is
A voltage signal output by the piezo load sensor 25 in accordance with the acting force that the shock absorber 2 receives from the road surface is output to the CPU 4a as a damping force change rate detection signal, and a signal obtained by integrating the voltage signal is output as a damping force detection signal C, PU4a
It is configured to output the signal to a low-pass filter 55.

Among the output components of the damping force detection circuit, the components that have passed through the low-pass filter 55 are output to the bypass filter 56.Low-pass filter 55 and bypass filter 5
6 (hereinafter referred to as a tilting component detection signal) is output to the CPU 4a.

The low-pass filter 55 passes signals having a frequency of approximately 1.3 [Hz] or less. On the other hand, the bypass filter 56 passes signals having a frequency of approximately 1°0 [day 2] or higher. Therefore, the damping force detection circuit 54
When the damping force detection signal output from the damping force detection signal passes through the low-pass filter 55 and the bypass filter 56, among the components of the damping force detection signal, frequencies 1. A tilting component detection signal having a frequency near the sprung mass resonance frequency with a frequency of 0 [Hz] or more and a frequency of 1.3 [Hz] or less is extracted.

Therefore, the CPU 4 a [1 detects the damping force change rate detection signal and the damping force detection signal outputted by the damping force detection circuit 54, and the tilting component that has passed through the low-pass filter 55 and the bypass filter 56 among the components of the damping force detection signal. Based on the signal and the output signal from a waveform shaping circuit 57 that shapes and outputs the detection signal of the steering sensor 50 etc. into a signal suitable for processing in the CPU 4a, the road surface condition, the driving condition of the vehicle, etc. are determined, In order to switch the degree of damping force of the shock absorber 2 according to the result, a control signal is output to the corresponding high voltage application circuit 58.

A high voltage application circuit 58 receives a high voltage from a high voltage power supply circuit 62 that outputs a drive voltage for driving the piezo actuator [1 CPU 4a] The damping force is applied to the actuator 27 to drive it, and the damping force of the shock absorber 2 is switched in accordance with the damping force switching signal. To explain in more detail, C
When a low level signal is input as a damping force switching signal from PU4a, a high voltage of +500 volts is applied to extend the piezo actuator 27, and conversely, when a high level signal is input as a damping force switching signal, a negative voltage is applied. It is configured to switch the voltage to -100 volts and apply it to contract the piezo actuator 27.

Therefore, when the damping force characteristic of each shock absorber 2 (upper high voltage is applied to extend the piezo actuator 27), the first liquid in the shock absorber 2 is Chamber 21 and second liquid chamber 2
The damping force becomes soft because the flow rate of the hydraulic oil flowing between Becomes powerful (hard).

Next, the damping force control processing performed by the suspension control device 1 of this embodiment having the above-described configuration will be explained based on the flowcharts of FIGS. 5 and 6. The routines shown in each figure (each of which is repeatedly executed at fixed time intervals by the above interrupt processing) are summarized as follows.

■Damping force control routine (Fig. 5) This routine is the main routine, and it judges the road surface condition mainly by the damping force change rate of the shock absorber 2. The damping force is controlled to be high or low by determining the tilting state of the vehicle.

■Tilt condition detection routine (Fig. 6) This routine is executed independently on the right wheel side and the left wheel side of the vehicle body, and the low-pass filter 55
Based on the tilting component detection signal that has passed through the bypass filter 56, each flag indicating the occurrence or termination of tilting of the vehicle body is set or reset.

First, the damping force control routine will be explained. Damping force control routine (Table 1) Although the damping force control routine is executed for each wheel, there is no change in the content of the control, so one of them will be explained as an example. In this routine, as shown in the flowchart of FIG.
). This hard priority switching flag HFLL is a flag that is set in step 130 of the damping force control routine, with reference to the processing result of the tilt state detection routine (FIG. 6), which is a subroutine, in the following step 120 of this damping force control routine. By determining the set/reset state in step 100, the processing performed in the damping force control routine is switched as follows.

If it is determined in step 100 that the hardware priority switching flag is not set (step 110), normal damping force control processing based on the road surface condition is performed. Driving status (steering angle) based on the detection signal of

This routine (one of the routines mentioned here among those performed for each wheel)
Shock absorber 2 (2FR, 2
(FL, 2RR or 2RL) damping force detection circuit 54
The road surface condition is determined based on the damping force change rate signal from
Depending on the result, the setting of the damping force of the shock absorber 2 is switched to either soft or hard suspension. That is, in general, when the damping force change rate signal exceeds a predetermined threshold, the suspension is switched from hard to soft 1-1, and when the signal continues to be below the threshold for a predetermined period, the suspension is switched. Switch from software to hard. Therefore, if the road surface is generally in bad condition, it will be soft, and if the road is flat, it will be hard.

After this damping force control process (step] ]O), a process of determining whether one of the tilt start flags SFR and 5FI-, which are processed in mutually independent tilt state detection subroutines, is set (step 120) Do this.

As will be detailed later, the tilt start flag SFR is based on the situation of the right wheel of the vehicle (front wheel 5FR or rear wheel RR is determined in the tilt state detection subroutine); The left wheel of the vehicle (front wheel 5FL or rear wheel 5RL is determined by the tilt start flag 5FRI:
It is characterized in that the cards are processed independently from each other based on the situation of the same side (the same side as the one on the left side), and when a sign of the occurrence of a tilt is detected, the cards are treated as ``1''.

If it is determined that one of the tilt start flags SFR and SFL has been set (step 120), the process of setting the above-mentioned hardware priority switching flag ``(step 130)'' is performed, and this routine is ended.

On the other hand, if it is determined in step 100 that the hardware priority switching flag is set, a tilt prevention execution process (step 40) is performed to prevent tilt, which is the main cause of car sickness.

In this execution process, the damping force of the shock absorber 2 is prioritized to be set to a high damping force regardless of the road surface condition (this process is performed for all shock absorbers 2
simultaneously in the damping force control routine for
If the suspension is soft, switch to hard, and if it is hard, keep it as it is.

After the above-mentioned tilt prevention execution process (step 140), a determination process (step 150) is performed to determine whether both tilt end flags EFR and EFL are set, which are processed in mutually independent tilt state detection routines. As described in detail later, the above-mentioned tilt end flag F"R is based on the situation of the right wheel of the vehicle (front wheel 5FR or rear wheel 5RR is the same side as for the tilt start flag S"R). On the other hand, the tilt prevention start flag E is based on the condition of the left wheel of the vehicle (front wheel 5FL or rear wheel 5R1- are on the same side with respect to the tilt start flag SFR).
They are processed independently of each other, and are set when each is recognized to have reduced the tilt.

If both tilt end flags EFR, EFLh< are set (step 150), it is determined that the risk of tilt occurrence (resolved) is 7, and the process of resetting the hardware priority switching flag HF described above is performed (step 160). .

When the hard priority switching flag is reset, the next time this routine is executed, the normal damping force control processing based on the road surface condition in Step 1] 0 will be performed, and if the road surface condition is bad, the suspension will be softened and the road surface If the condition is flat, make it hard.

As described above, in the damping force control routine, if one of the tilt start flags SFR and SFL is set to 1-, if there is a strong possibility that the tilt will increase throughout the vehicle, priority is given to hard. Set the switching flag HF and press 4.
Preferentially set the total wheel suspension to bird to prevent the occurrence of tailgating.

In addition, after the tilt occurrence prevention process, the tilt end flag EF is set.
If it is determined that both R and EFI- have been reset to 1 or higher, the hard priority switching flag port F is reset, assuming that the entire vehicle no longer suffers from turbulence, and the process of preferentially setting the suspension stiffness to hard ends. do.

The following is a tilt state detection routine that processes the tilt start flag SFR and the tilt end flag EFR that are referenced in the damping force control routine (or is independent from this routine and processes the tilt start flag SFL and the tilt end flag EFL). tilt state detection routine)
will be explained based on the flowchart in FIG. still,
One of the independently executed tilt state detection routines relates to the left side L of the vehicle, and the other relates to the right side of the vehicle, but since the contents of the processing are the same, the processing for the right side will be explained here as an example.

The tilting state detection routine shown in FIG. 6 (step 200 in which it is determined which damping force control mode selected by the mode selector switch MS is "normal" or "sport") is "normal". Load the damping force data PR for the right rear wheel 5RR (
Step 210), in the case of "Sport" (upper right front wheel 5
The damping force data PR for FH is read (step 220).

Read damping force data PR [& low pass filter 5
This data is constituted by a tilting component detection signal having a frequency of about 1.0 to about 1.3 [day 2] inputted through the filter 5 and the bypass filter 56.

In this embodiment, even if the vehicle is traveling on the same road surface at the same location, after step 200 (i.e., step 210, 22
0)) Depending on the difference in the damping force data PR read,
There may be a difference in the processing results of this tilt state detection routine,
As a result, the control in the damping force control routine that refers to the processing result becomes different.

For reference in the explanation that follows, FIG. 7(A) shows a graph showing the relationship between the damping force data PR of the right front wheel 5FR and time when driving on a certain road surface, and FIG. ) shows a graph showing the relationship between the damping force data PR of the right rear wheel 5RR and time for the same road surface.

Reading of damping force data PR (step 210 or 2)
20), the process (step 230) is executed to determine whether or not the hardware priority switching flag H is set to the value 1. If it is determined that the hardware priority switching flag H is not set, the Step 240 and subsequent steps are executed to determine the start conditions for the tilt prevention execution.Meanwhile, in step 230, the hardware priority switching flag
If it is determined that the start condition is set, the process skips the process of determining the start condition and proceeds to the process of determining the end condition of the anti-tilt execution shown below in the connector (2) in FIG.

Start Condition Determination Process 1 The damping force data PR read in above is monitored, and when a condition indicating a sign of occurrence of tilt is satisfied, the tilt start flag S is set to R.

In this determination process, first, shock absorber 2FR or 2RR (that is, in step 200, shock absorber 2FR in normal mode, shock absorber 2R% in sport mode).
A process (step 240) is performed to determine whether the setting of the damping force of the shock absorber 2FR or 2RRJ is low damping force (soft) or high damping force (hard). If it is determined that the damping force setting is low (if the damping force data of shock absorber 2FR or 2RR is
A determination process (step 250) is performed to determine whether the absolute value of R is greater than or equal to the lower threshold 811. For example, li rYESJ is determined immediately after time t1 in the graph of FIG. 7(A) and immediately after time T1 in the graph of FIG. 7(B).

On the other hand, if it is determined in step 240 that the setting is a high damping force (step 260), the absolute value of the damping force data PR of shock absorber 2FR or 2RR is determined to be higher than or equal to the high side threshold SL2. The high threshold SL2 is a larger value than the low threshold SL1, and even on the same road surface, if the level of damping force generated while the vehicle is running is set to high damping force (hard), the damping will be low. This value compensates for being higher than the force (soft) setting.

In step 250 or 260, damping force data P
If it is determined that R is within the range of SLI, ±SL2 above each threshold value (from the damping force data PR of shock absorber 2FR or 2RR (from Processing to clear the counter CSR for timing the start condition determination period ΔTs (step 270), and the tilt prevention start flag S
A process for resetting the FR (step 280) is performed, and this process is temporarily terminated.

On the other hand, in step 250, the absolute value of the damping force data PR of the shock absorber 2FR or 2RR is determined to be the threshold value 81.
1 or more, or in step 260, the damping data PR of the shock absorber 2FR or 2RR is removed.
If it is determined that the value is equal to or higher than the threshold value 51-2, there is a possibility that the vehicle is detecting a sign that the vehicle is swaying.
Judgment period △T S The judgment period △ is determined by the process of incrementing the color time counter C3RP (step 290) and incrementing the counter C5R (whether or not the incremented counter csRh is greater than or equal to the judgment value VS). A process (step 300) is performed to determine whether or not the word 1 of Ts is completed (-)□.

For example, as shown in the graph of FIG.
] (in the case of FIG. 7(A)) or after time T1 (in the case of FIG. 7(B)), the damping force continues to reach the threshold value St.
When the value exceeds 1-L, the absolute value of the damping force data PR is continuously determined to be equal to or greater than the 1-2 threshold 311 at step 250 every time the process color is repeated in the anti-tilt control subroutine. In some cases, the counter C5R is not reset and increases one after another in step 290 to increment 1 - the card judgment value VS. , Mi, the determination period ΔTSE expires at time t2 (in the case of FIG. 7(A)) or time 1-2 (in the case of FIG. 7(B)) IJ.

As in this example, counter C5R increases and step 3
If it is determined that the threshold value is equal to or higher than the judgment value VS in 00, it is determined that a sign of occurrence of tilting has been detected.2 Process of setting the tilting prevention start flag SrRt (step 310)? ;Execute. On the other hand, if the counter CSR becomes less than or equal to the judgment value VS, it is determined that the reading A7 damping force data PR does not indicate a sign of the occurrence of tilting, and the water treatment is terminated.

In step 310, if the tilting start flag S is set to ``R'', the hard priority switching flag is set in the damping force control routine as described above (fifth
Referring to step 130 in the figure), a tilt prevention execution process (step 140) is executed in which the damping force of the shock absorber 2 of all four wheels is switched to a higher damping force. In the example of FIG. 7, the suspension of all wheels becomes hard from time t2 (in the case of FIG. 7(A)) or from time T2 (in the case of FIG. 7(B)).

Furthermore, in the subroutine for detecting the tilting state for the left side of the vehicle (not shown in Figure 12), when the tilting start flag 5FI- of the left wheel 5FL or 5R1- is set, the tilting prevention execution process (step 5 in FIG. 5) is also performed in the damping force control routine. 140) is performed.

In the start condition determination process described above, the counter C
For example, the condition that SR be equal to or greater than the judgment value VS, that is, that the damping force continuously exceed the threshold values SLI and SL2 during the judgment period ΔT 5, is based on the low-pass filter 5.
This is to supplement the accuracy of No. 5 and improve the determination accuracy. Due to the characteristics of the filter 55, some components with frequencies slightly higher than frequencies 1 and 3 [mouth Z] pass through, but these components, which have nothing to do with tilting, are immediately rejected even if they exceed the 1-thresholds SLI and SL2. stand down. Therefore, by making it a requirement that the damping force be continuously equal to or greater than the threshold value during the determination period ΔTs, as described above, the possibility of erroneous determination due to high frequency components that quickly fall can be eliminated.

Next, the termination condition determination process (below connector ①) shown in FIG. 6 will be explained.

The end condition determination process is performed when the tilt start flag SFR is set in the start condition determination process as described above, or when it is determined in the first step 100 that the hardware priority switching flag HF is set. It will be done. The judgment process is performed using the read damping force data P.
The outline is that R is monitored from 1 to 1 and is activated when there is a possibility that execution of the C1 tilt prevention process should be terminated.

In this determination process, first, step 210 or 220
A judgment process (step 320) is executed to determine whether the absolute value of the damping force data PR of the shock absorber 2FR or 2RR read in is less than a predetermined 1/threshold value 813. In step 320, the absolute value of the damping force data PR is the threshold value S.
If it is determined that the damping force is equal to or higher than L3 (see FIG. 7), the damping force is still large. Therefore, since the vehicle will be subject to tailgating if the tailgating prevention execution is terminated, the process (step 330) of counting the counter CER for timing the determination period ΔTe of the termination condition (described later) is executed, and the tailgating prevention end flag is also set. A process for resetting the EFR (step 340) is performed, and this process is temporarily terminated.

On the other hand, in step 320, the damping force data PR is set to the threshold value ±
It is determined that the damping force is within the range of SL3 (for example, immediately after time t3 or after time t5 in FIG. 7(A), and for example at time T3 in FIG. 7(B)).
In this case, there is a possibility that the end condition is satisfied for the wheel for which the damping force data PR has been read. )
Then, a process (step 360) is performed to determine whether or not the incremented counter CER is equal to or greater than the determination value 91, that is, whether or not the measurement of the end determination period ΔTe has been completed by incrementing the counter CEH.

The counter CER is incremented one after another in step 350 when it is continuously determined in step 320 that the damping force data PR is within the range of threshold value ±SL3 each time the anti-tilt control routine is repeated. Tag Increases to the judgment value VE.

For example, time t3 shown in FIG. 7(A) or time t3 shown in FIG. 7(B)
), the counter CER increases continuously because the damping force data PR is within the range of the threshold ±SL3, but the damping force does not change at time t4 or at time T4. Since the data PR is outside the range of threshold value ±SL3, it does not increase to the judgment value VE which is reset in step 330.In such a case, the counter CER is determined to be less than the judgment value VE in step 360. If the process ends, it is determined that there is a risk of occurrence of tilt, and after executing the process of resetting the tilt end flag EFR (step 340), the process ends.

On the other hand, after the time t5 shown in FIG. 7(A) or the time T5 shown in FIG. 7(B), the damping force data PR of the shock absorber 2FR or 2RR continues to be within the range of the threshold value ±SL3. Therefore, the counter CER increases to the judgment value VE. Therefore, at time t6 or time T6 when the counter CER increases to the judgment value VE, it is determined that the counter CER is equal to or greater than the judgment value V[, At least shock absorber 2FR or 2R
Based on the damping force data PR of R, it is determined that there is a small possibility that the steering wheel will occur even after the steering wheel prevention process is completed, and the steering wheel end flag EFR for the right side of the vehicle is set (
step 370).

In FIG. 7(A), time t6. In Figure 7(B), time T
6, the end condition determination period ΔTe expires.

As described above, in step 370, the right-side vehicle tilt end flag EFR is set, and similar processing is performed in the vehicle tilt state detection routine for the left side of the vehicle (the front wheel or the rear wheel is the same as the right side of the vehicle), not shown. When the left side tilt end flag E of the vehicle is set by execution, the hard priority switching flag HF is reset (step 160) in the damping force control routine as described above.

Thereafter, in the damping force control routine (step 110), the damping force control process based on the normal road surface condition is performed, and if the road surface condition is bad, the suspension is made soft, and if the road surface is flat, the suspension is made hard.

In the termination condition determination process, the condition is that the counter CSR is equal to or higher than the determination value 93, that is, the damping force data PR remains within the threshold value ±SL3 during the determination period ΔTeO. As already mentioned, Fig. 7 (A
) or after time T3 in FIG. 7(B), even if the damping force data PR falls within the range of threshold value ±SL3, the damping force data PR at time t4 or time T4f immediately thereafter This is because it is better to leave the termination condition not satisfied when the value again falls outside the range of threshold ±SL3, because this will not lead to excessively frequent changes in suspension settings and will not give an unnatural feeling to the occupants. .

For this purpose, the damping force data P is set during the termination condition determination period ΔTe for a period longer than the period of vibration near the sprung mass resonance frequency of L frequency 1.0 [H2] to 1.3 [Hz].
It is set to monitor R.

As explained above, 1: In the tilt condition detection subroutine, the mode changeover switch MS determines whether signs of the onset and end of tilt are detected at the front wheels or the rear wheels of the vehicle.
It changes depending on. That is, the sign is detected at the rear wheel in the "normal" mode (the front wheel in the lulLr sport mode).

Therefore, the damping force control routine, which is the main routine, is a routine for detecting each tilting state regarding the front wheels of the vehicle (i.e., a routine for detecting tilting on the front wheels) when the mode changeover switch MS is selected as "sport". Flags to be set and reset SFR, SFL, EFR
, EFL, the damping force of the shock absorber 2 is controlled by a damping force control routine. As a result, as illustrated in FIG. 8(A), the arrow
When the road surface on which the vehicle is traveling becomes rough, the 8th
As shown in Figure (B), the suspension on the front wheel side is frequently set to a soft state depending on the road surface condition (according to step 110 in Figure 5), and when it is detected that the front wheel side is in a heated state, the suspension on the front wheel side is In addition, the suspension on the rear wheel side is prevented from being in a soft state and maintained in a hard state (according to step 140 in FIG. 5), regardless of the state of the rear wheel's swing.

In other words, if the front wheels of the vehicle become a little loose, the suspension of the entire vehicle immediately becomes hard and the movement of the springs is suppressed. As a result, the suspension generally switches to a hard position with good responsiveness, and the overall control becomes more focused on steering stability.

On the other hand, when the mode changeover switch MS is set to "Normal", the main routine, the damping force control routine, is a routine for detecting each tilting state for the rear wheels of the vehicle (i.e., detecting tilting at the rear wheels). flags SFR, SFL, EF set and reset by routine)
The damping force of the shock absorber 2 is controlled while referring to R and EFL. As a result, Figure 8 (A
), when the road surface on which the vehicle is running becomes rough,
J shown in Figure 8 (C): Sea urchin, the front wheel (
JIIL The suspension is frequently set to a soft state in the order of the rear wheels (according to step 1] 0 in Figure 5), and then only when the rear wheels are detected to be in a heated state is the suspension set to the soft state (11L rear wheels). By prohibiting the soft state of both suspensions and maintaining the hard state (according to step 140 in FIG. 5), tilting is prevented.In other words, even if the entire vehicle becomes slightly tilted, the suspension is kept in the hard state. (than when the upper mode selector switch MS is selected to "Sport")
The suspension becomes relatively gentle, and as a result, the suspension tends to remain soft. Therefore, the suspension control as a whole is tailored to give priority to ride comfort.

As explained above, in the suspension device of this embodiment, by switching the location where the tilt is detected to the front wheel side or the rear wheel side of the vehicle using the mode changeover switch MS,
The control mode of the damping force of the shock absorber can be switched to a ride comfort priority mode or a steering stability priority mode.

That is, in the suspension device of this embodiment, two clearly different shock absorber control modes ("normal" and "sport") can be set.

Incidentally, in the above embodiment, the tilting is detected based on the damping force change, but instead, it may be detected by a stroke sensor or the like that detects the relative vehicle height of the sprung mass and the sprung mass.

A second embodiment of the suspension of the present invention will be described. The second embodiment differs from the first embodiment only in the tilt state detection routine in the following points.

In the first embodiment (by the mode changeover switch MS,
The damping force data PR to be read for tilt detection is set to the front wheel suspension IL.
Although the switch was made to the rear wheel side, in the tilt state detection routine of the second embodiment, [the damping force data PR of the front wheel side is always read, and the damping force data PR of the rear wheel side may also be always read.] , the determination value vS is switched in a step corresponding to step 300 of the tilt state detection routine of the first embodiment in accordance with the selection of the mode changeover switch MS. In other words, with the mode selector switch MS,
When "Normal" is selected, a large judgment value Vsb
It is assumed that when "Sports" is selected, the judgment value Vss is small.

In the second embodiment, when "Normal" is selected with the mode changeover switch MS, it is difficult to start the anti-tilt control.
Therefore, the suspension tends to become soft,
As a result, emphasis is placed on ride comfort.On the other hand, when "Sport" is selected, anti-rolling control is likely to start, which tends to make the suspension harder, and as a result, emphasis is placed on steering stability.

In this way, in the second embodiment, the mode changeover switch M
Based on switching the determination value VS by selecting S, shock absorber control modes with clearly different damping force characteristics can be set.

In the second embodiment, the judgment value vS is switched by the mode changeover switch MS, but along with or instead of this switching, the threshold value 5L1 (along with SL2) is also changed.
, threshold value SL3, and judgment value VE, a similar effect can be obtained by switching one or more of them.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. For example, 1'L may be used on one side of the left and right wheels instead of both the left and right wheels to obtain the damping force for detecting the occurrence of vehicle tilt.

In this case, the processing performed by the electronic control device 4 can be simplified. Also, the damping force of shock absorber 2 is 3
It may be possible to set multiple stages. In this case, in addition to setting the control mode of the damping force characteristic based on the switching between multiple stages, it is also possible to set the control mode of the damping force characteristic based on the switching of the tilt detection wheel as mentioned in the above embodiment. As a result, it is possible to set a wider variety of control modes.Furthermore, in the above embodiment, when no tilting is detected, the road surface condition is determined mainly based on the signal of the damping force change rate of 1, and the damping of the shock absorber is determined. Although the force characteristics are controlled, the control may be performed based on other signals, such as signals from a vehicle height sensor.

Further, in the above embodiment, the threshold value SL3 of the end condition is larger than the threshold value SLI of the start condition, but depending on the vibration characteristics of the vehicle, the threshold value SLI and the threshold value SL3 may be the same. Various relationships can be considered for the values. In addition, in the above embodiment, the threshold value of the starting condition (±SLI,
±5L2) and end condition threshold (±5L3)
As shown in FIG. The absolute value of the threshold value on the negative sign side may be different, for example, the former may be set relatively larger than the latter. Generally, the damping force generated by the shock absorber 2 differs in magnitude between its extension side and its contraction side, but with the above configuration (a threshold value can be set to compensate for the difference in damping force between the upward extension side and the contraction side), , the accuracy of determining start conditions and end conditions is improved.

Furthermore, the configuration for determining the start condition and the end condition may be configured using discrete circuit elements instead of using a microcomputer.

Soumachi Ω Effect As detailed above, the vehicle suspension control device of the present invention generates vibrations at a frequency near the sprung mass resonance frequency in the vehicle body according to the selection of the I-1 mode switching means. Since the responsiveness of the damping force characteristics of the shock absorber to a hard forced setting or the responsiveness of releasing the forced setting can be changed, the overall control characteristics of the shock absorber's damping force can be switched based on the above responsiveness. becomes. That is, clearly different control modes (ie, control modes for the damping force characteristics of the shock absorber) can be set.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram showing the overall configuration of a suspension control device as an embodiment of the present invention, and FIG. 3(A) is a block diagram of the shock absorber. Partial sectional view showing the structure, Figure 3 (B
) is an enlarged cross-sectional view of the main parts of the shock absorber, FIG. 4 is a block diagram showing the configuration of the electronic control device of this embodiment, and FIG.
Figure 6 is a flowchart showing the damping force control routine, Figure 6 is a flowchart 1-1 showing the tilt state detection routine, Figure 7 is a flowchart showing the road surface condition, the damping force data PR of the right front wheel 5FR or the right rear wheel 5RR, and the time. A graph showing the relationship, FIG. 8, is an explanatory diagram showing the road surface condition, the damping force data PR, and the control situation of the shock absorber. 2FL, 2FR, 2RL, 2RR... Variable damping force shock absorber 4... Electronic control unit 25FL, 25FR, 25RL, 25RR...
・ Piezo load sensor 27FL, 27FR, 27RL, 27RR...
・Piezo actuator 54...Damping force detection circuit 55...Low pass filter 56...Bypass filter 58...High voltage application circuit 62...High voltage power supply circuit MS...Mode selection switch

Claims (1)

[Claims] 1. Detecting changes in vehicle vibration based on changes in road surface conditions;
A suspension control device that suppresses vehicle body vibration by changing the damping force characteristic of a shock absorber to a higher side or a lower side, comprising a vehicle body vibration detection means for detecting a change in vibration of the vehicle body, and a system based on a detection signal from the vehicle body vibration detection means. , a vibration extraction means for extracting vehicle body vibration at a frequency near a sprung resonance frequency of the vehicle body, and the shock absorber whose damping force is subject to change when the amplitude of the extracted vehicle body vibration exceeds at least a threshold value. damping force setting means for forcibly setting the damping force characteristic of the shock absorber to the higher side; forced setting canceling means for canceling the forced setting based on the extracted vehicle body amplitude; and control of the damping force of the shock absorber. a mode switching means for switching modes, and responsiveness from the occurrence of vibration at a frequency near the sprung mass resonance frequency in the vehicle body to the forced setting, or responsiveness to the cancellation of the forced setting, depending on the selection of the mode switching means. A suspension control device comprising: responsiveness changing means for changing the response.